The invention relates to improvements in methods of and in apparatus for ascertaining the transverse dimensions of elongated articles or commodities, especially the diameters of rod-shaped smokers' products. More particularly, the invention relates to a method and to an apparatus which can be utilized to ascertain transverse dimensions of single rod-shaped articles or to simultaneously ascertain the transverse dimensions of plural rod-shaped articles, such as continuous cigarette rods, continuous filter rods, discrete plain or filter cigarettes and the like. Still more particularly, the invention relates to improvements in methods and apparatus wherein at least one source emits a beam of radiation which impinges and is partially intercepted by a stationary or moving rod-shaped article, and wherein the non-intercepted portion of the beam is evaluated by an arrangement, such as an optical system, which serves to generate signals denoting the diameter of that portion of the article which partially intercepts the beam, normally for a relatively short interval of time.
When the method and the apparatus of the present invention are put to use in connection with the determination of transverse dimensions of rod-shaped or substantially rod-shaped articles or products of the tobacco processing industry, such as plain or filter cigarettes, cigarette rods or filter rods, the term “rod-shaped articles” or “rod-shaped products” (hereinafter referred to as “rod-shaped articles”) is intended to encompass or embrace all kinds of rod-shaped articles which are being turned out and/or processed by the tobacco processing industry, i.e., also cigars, cigarillos, papyrossy and many others. The determination of transverse dimensions (such as diameters) of the articles can be carried out during any one of numerous stages of the making and/or processing thereof, e.g., in a cigarette rod making machine or downstream of such machine. Thus, the improved method and apparatus can be put to use to ascertain the transverse dimensions of continuous rod-shaped articles (e.g., cigarette rods issuing from a cigarette making machine and advancing into the range of a so-called cutoff which subdivides the rod into a series or file of discrete plain cigarettes of unit length or multiple unit length). Alternatively, the improved method and apparatus can be resorted to in order to ascertain the transverse dimensions of discrete plain or filter cigarettes, cigars, cigarillos, filter rod sections of unit length or multiple unit length and the like.
The diameter is a very important parameter in connection with the making of smokers' products, such as plain or filter cigarettes. Therefore, it is customary and desirable to ascertain the diameter in order to ensure the making of highly satisfactory smokers' products which are pleasing to the eye, which can be properly attached to adjoining rod-shaped products and/or which can be properly assembled with identical or analogous rod-shaped products for confinement in boxes, packs, cartons or other types of containers. In many instances, a presently known ascertainment of diameters (i.e., of transverse dimensions) is being carried out while the rod-shaped articles move through the diameter-ascertaining apparatus lengthwise, i.e., in the direction of their longitudinal axes, either continuously or discontinuously (e.g., stepwise).
A drawback of the presently known methods and apparatus of the just outlined character is that they are not sufficiently reliable if the rod-shaped articles are not exactly round, i.e., if their cross-sectional outlines (in planes which are normal to their longitudinal axes) are not exactly circular or sufficiently close to circular outlines. For example, European patent No. 0 909 537 A1 discloses a diameter ascertaining apparatus wherein a source of radiation emits a wide beam of parallel (collimated) rays and directs the beam against a mirror which is arranged to deflect the beam through 90° so that the beam impinges upon a radiation processing or evaluating unit. The rod-shaped article extends lengthwise in such a way that it is parallel to the reflecting surface of the mirror and at right angles to the direction of propagation of the radiation. The arrangement is such that a first portion of the radiation impinges directly upon the rod-shaped article and a second portion of the radiation reaches the article subsequent to deflection by the mirror. In other words, the radiation reaching the evaluating unit includes a first section which is being propagated from the source directly to the evaluating unit and a second section which is adjacent the first section and reaches the evaluating unit subsequent to deflection by the mirror. The two sections represent those diameters of the article which cross two axes that are normal to each other. The just described patented apparatus is capable of ascertaining the diameters of rod-shaped articles which need not or should not turn about their longitudinal axes; this is an important advantage when the articles are endless rods containing natural, reconstituted and/or substitute tobacco and/or filter material for tobacco smoke. However, these apparatus also exhibit a serious drawback, namely that the measurements which can be carried out therewith are not sufficiently reliable. This is attributable to the fact that the patented apparatus can ascertain only two diameters of a rod-shaped article, i.e., the number of measurements in a selected plane extending at right angles to the axis of the elongated rod-shaped article is insufficient to permit a detection of portions which might be bounded by surfaces that depart (even significantly) from surfaces on a cylindrical article.
German patent No. 195 23 273 A1 discloses a second method of and a second apparatus for ascertaining the diameters of rod-shaped articles of the tobacco processing industry, e.g., of cigarettes and the like. The article to be tested rotates about its longitudinal axis during movement through a stationary apparatus. The thus manipulated article is exposed to radiation in such a way that at least a certain amount of radiation not intercepted by the article being tested is utilized to generate an electric first signal. Several of the thus obtained first signals are processed to furnish a second signal denoting the diameter of the article. The just described second apparatus exhibits the advantage that its accuracy exceeds those of other presently known apparatus; however, the versatility of the second apparatus is unsatisfactory, particularly or primarily because it cannot be put to use for the determination of diameters of rod-shaped articles which do not turn about their longitudinal axes.
Commonly owned U.S. Pat. No. 5,715,843 (granted Feb. 10, 1998 to Hapke et al. for “METHOD OF AND APPARATUS FOR MEASURING THE DIAMETERS OF ROD-SHAPED ARTICLES OF THE TOBACCO PROCESSING INDUSTRY”) discloses an arrangement for ascertaining the diameters of rod-shaped articles of the tobacco processing industry while the articles advance sideways along the periphery of a rotary drum-shaped conveyor and are rotated about their longitudinal axes as a result of frictional engagement with a rolling member adjacent the periphery of the conveyor. Successive articles intercept a beam of radiation issuing from a laser, either once or more than once, and the amounts of intercepted radiation are indicative of the diameters of the respective articles. This apparatus is quite satisfactory for the ascertainment of diameters of rod-shaped articles of finite length while the articles perform the aforementioned composite movements.